CEOP PRODUCTION ON FALLOW LAND AT SAN ANTONIO. 5 



This comparatively light vegetative growth appears to have been 

 favorable to the production of grain. In 1912 and 1913, especially 

 the latter season, oats on the rotation plats lodged badly, owing to 

 excessive vegetative growth. It has been found at San Antonio that 

 any treatment which has a tendency to retard the early vegetative 

 growth of the oat plant results in increased yields of grain. An 

 instance substantiating this statement is afforded by the unfavorable 

 results from manuring on land planted to oats to be harvested for 

 grain. In a 4-year test with oats, manuring has noticeably decreased 

 the yield of grain in two out of the four years, while in the other two 

 years the yields were practically the same as those obtained from 

 unmanured land. It appears, therefore, that the increase in yield of 

 oats on fallowed land has not been due to the fact that conditions 

 were more favorable to growth, but rather to a depressing effect on 

 the vegetative growth. 



Crops grown on fallowed land have invariably shown irregular and 

 slow early development as compared with the same crops on other 

 plats. The corn and cotton on the fallowed plats have been notice- 

 ably smaller than on the other plats in the rotation experiments, and 

 the plants have lacked uniformity in size and appearance. Observa- 

 tions on other plats* of the experiment farm where cotton has been 

 grown on fallowed land corroborate this conclusion. While the 

 differences with oats have not been so marked, in 1913 the oats on 

 fallowed land were smaller and made slower growth than on land 

 continuously cropped or having other treatments. On account of 

 the difficulty with the lodging of grain crops, as already indicated, the 

 depressing effect of fallowing on the growth of the plants results in 

 high yields of oats, while it has the opposite effect on corn and 



cotton. 



SOIL-MOISTURE STUDIES. 



Soil-moisture determinations have been made on the fallowed plats 

 considered in this report and also on the continuously cropped plats 

 devoted to the same crops. Samples have been taken monthly or 

 oftener during the summer throughout the three years. A standard 

 soil tube was used for securing the samples. At each sampling two 

 cores were taken from different parts of the plat, corresponding foot- 

 sections being composited to a single sample. Thus either three or 

 six samples were secured from each plat, depending upon the depth 

 to which the sampling was done. In most cases samples were taken 

 to a depth of 6 feet. 



In figures 2, 3, and 4 the diagram at the top shows the crop, 

 stubbie, and fallow periods for each plat considered in this report, 

 and the curves below show the moisture content of the different 

 plats at the time the moisture determinations were made during the 

 four years from 1910 to 1913, inclusive. 



